1. Field
The present disclosure relates to a lower rail structure of a sliding door for a vehicle, and more particularly, to a lower rail structure of a sliding door for a vehicle capable of increasing support rigidity of a lower rail.
2. Background
Generally, a sliding structure for a vehicle has a structure in which it is opened or closed by installing rails at an upper portion, a central portion, and a lower portion of a body and sliding upper, central, and lower rollers installed on a door on the rails, respectively.
A conventional lower rail structure of a sliding door for a vehicle is configured to include an upper rail 20 provided in a side sill 10, a lower rail 30 provided over the upper rail 20, and a side sill lower upper panel 40 having the lower rail 30 fixed thereto, as shown in FIG. 1, wherein one end of the side sill lower upper panel 40 fixed to the side sill 10 in a cantilever form and one side of an upper portion thereof is fixed to a floor panel 50.
In addition, the upper rail 20 and the lower rail 30 are provided with an upper roller 61 and a lower roller 62 mounted on a door 60 and slidably formed, respectively. Therefore, the door 60 is opened or closed while being slid along the upper rail 20 and the lower rail 30.
However, in the lower rail structure of a sliding door for a vehicle according to the prior art, when a passenger getting in a second row of the vehicle steps on the side sill lower upper panel 40, a vertical load is generated at the side sill lower upper panel 40 due to a load of the passenger, such that the side sill lower upper panel 40 is deformed. In addition, the lower rail 30 is deformed due to the deformation of the side sill lower upper panel 40, such that a sliding property of the lower roller 62 is deteriorated. Therefore, the door is not smoothly opened or closed.